System for validating velocities of components in a vehicle

ABSTRACT

A system for validating velocities of components in a vehicle uses sensor measurements and mathematical relationships between the vehicle components to validate the velocities. A controller or controllers receive speed or velocity inputs and mathematically combine the velocities of more than one of the vehicle components. The velocities of at least one of the vehicle components is validated when the mathematical combination meets at least one predetermined criterion. The validated velocity or velocities are then communicated to at least one of the vehicle components.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.10/605,288 filed 19 Sep. 2003, which is hereby incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the operation of a hybridelectric vehicle, and more particularly, to a diagnostic system andmethod for validating engine and motor velocities in a vehicle.

2. Background Art

A number of different types of vehicles include one or more electricmotors and/or generators in addition to an internal combustion engine.For example, a hybrid electric vehicle may have a separate motor andgenerator, or a single unit in which the motor and generator arecombined, in addition to a gasoline or diesel internal combustionengine. Other vehicle architectures may similarly include an engine andone or more electric motors. As the number of torque generating devicesincreases, control of such vehicles becomes increasingly complex.

Effective control of a vehicle having a complex architecture, includingan engine and one or more electric motors and/or generators, may requireknowledge of the speed at which each of the torque generating devices isoperating. In addition, devices such as motors and generators can oftenrotate in either of two directions. Thus, in addition to the speed of adevice such as a motor or generator, it may also be important to knowthe direction in which the device is rotating. The combination of speedand the direction of rotation is the velocity of the device, a knowledgeof which is useful to control the vehicle.

Because of inaccuracies in measurement devices, such as sensors, and incommunications links, such as a controller area network (CAN), sensormeasurements may need to be validated to ensure their accuracy.Validation of the velocity of a torque generating device may require twoindependent speed measurements. The cost of providing a vehicle with twoseparate speed sensors for each torque generating device may beunacceptably high. Therefore, a need exists for a system and method forvalidating velocities of torque generating devices, such as engines andmotors, in a vehicle, wherein the velocities can be validated using asingle speed or velocity sensor for each torque generating device, andusing a knowledge of the relationships between the speeds of the devicesbased on the vehicle architecture.

SUMMARY OF THE INVENTION

Therefore, the present invention provides a method for validating engineand motor velocities in a vehicle, without using two separate speedsensors for the engine and two speed sensors for the motor. The methodincludes measuring engine speed, thereby facilitating a determination ofengine velocity. The velocity of a first motor is also measured. Theengine velocity and the velocity of the first motor are used in a firstequation, which includes the use of a first velocity relationship. Thefirst velocity relationship relates the engine velocity and the velocityof the first motor based on vehicle architecture. The first equation isdeterminative of whether a mathematical combination of at least theengine velocity and the velocity of the first motor is within a firstpredetermined speed range. The engine velocity and the velocity of thefirst motor are validated when the mathematical combination of at leastthe engine velocity and the velocity of the first motor is within thefirst predetermined speed range.

The invention also provides a method for validating engine and motorvelocities in a vehicle having an engine, a first motor, and a secondmotor. The method includes measuring engine speed, thereby facilitatinga determination of engine velocity. The velocity of the first and secondmotors is also measured. The engine velocity and the velocity of thefirst and second motors are mathematically combined to generate a firstcombined speed term. The first combined speed term is compared to afirst predetermined speed range. The engine velocity, the velocity ofthe first motor, and the velocity of the second motor are validated whenthe first combined speed term is within the first predetermined speedrange.

The invention further provides a system for validating engine and motorvelocities in a vehicle having an engine and at least one motor. Thesystem includes a first sensor configured to measure engine speed,thereby facilitating a determination of engine velocity. A second sensoris configured to measure the velocity of a first motor. A controller isin communication with the first and second sensors, and is configured toapply a preprogrammed algorithm to at least the engine velocity and thevelocity of the first motor. The preprogrammed algorithm includes adetermination of whether a mathematical combination of at least theengine velocity and the velocity of the first motor is within a firstpredetermined speed range. The engine velocity and the velocity of thefirst motor are validated when the mathematical combination is withinthe first predetermined speed range.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a portion of a vehicle includinga system in accordance with the present invention;

FIGS. 2A and 2B are a flow chart illustrating a method in accordancewith the present invention;

FIG. 3 is a table defining equation variables and input ranges for eachof the variables; and

FIG. 4 is a schematic representation of a portion of a vehicle having adifferent architecture from the vehicle shown in FIG. 1, and analternative embodiment of the system shown in FIG. 1.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 shows a schematic representation of a system 10 in accordancewith the present invention. A vehicle, not shown in its entirety,includes an engine 12, a first motor 14, and a second motor 16. Theengine 12 and the first motor 14 are connected through a power transferunit, which in this embodiment is a planetary gear set 18. Of course,other types of power transfer units, including other gear sets andtransmissions, may be used to connect the engine 12 to the first motor14. The planetary gear set 18 includes a ring gear 20, a carrier 22, anda sun gear 24. An engine shaft 26 is connected to the carrier 22, whilea motor shaft 28 is connected to the sun gear 24. A motor brake 30 isprovided for stopping rotation of the motor shaft 28, thereby lockingthe sun gear 24 in place. Because this configuration allows torque to betransferred from the first motor 14 to the engine 12, a one-way clutch32 is provided so that the engine shaft 26 rotates in only onedirection.

The ring gear 20 is connected to a shaft 34, which is connected tovehicle drive wheels 36 through a second gear set 38. The second motor16 is also connected to the wheels 36 through a second motor shaft 40and the second gear set 38. The motors 14,16, the planetary gear set 18,and the second gear set 38 may generally be referred to as a transaxle42.

The first and second motors 14,16 are electrically connected to abattery 44. The battery 44 provides electrical power to one or both ofthe first and second motors 14,16 when they output mechanical energy tothe wheels 36. Alternatively, one or both of the motors 14,16 can act asa generator that can be used to charge the battery 44 when the vehicleis in a regenerative mode or when the engine is running. Moreover,either of the motors 14 or 16 could act as a generator to provideelectrical power to the other motor.

The vehicle architecture shown in FIG. 1 is but one of many differentarchitectures that can be used with the system 10. For example, asmentioned above, the planetary gear set 18 could be replaced withdifferent types of power transfer units. In addition, as explained morefully below with reference to FIG. 4, a disconnect clutch could beplaced on the engine shaft 26 to allow a mechanical disconnection of theengine output from the wheels 36. Moreover, different types ofelectrical output devices, such as a fuel cell or ultra-capacitor, maybe used in place of, or in conjunction with, a battery, such as thebattery 44.

A controller, in this embodiment, a powertrain control module (PCM) 46is provided for controlling the engine 12 and the motors 14,16. Althoughshown as a single unit, the PCM 46 may be made up of more than onecontroller. For example, rather than the single PCM 46, the engine 12and each of the motors 14,16 may have their own control unit in the formof a separate hardware device. Alternatively, the controllers for theengine 12 and the motors 14,16 may be software controllers that residewithin one or more hardware controllers, such as a vehicle systemcontroller.

In order to provide information to the PCM 46 about the speeds and/orvelocities of the various torque generating devices in the vehicle—i.e.,the engine 12 and motors 14,16—a number of sensors are used to takemeasurements and provide information to the PCM 46. A first sensor 48 isin communication with the PCM 46, and is configured to measure the speedof the engine 12, which facilitates a determination of engine velocity.The engine velocity includes not only the engine speed, but also thedirection of rotation. Because the engine 12 can only rotate in onedirection, the speed sensor 48 may be a simple speed sensor that doesnot measure the direction of rotation of the engine 12, since thedirection is already known. Thus, the speed sensor 48 providesinformation to the PCM 46 such that the velocity of the engine 12 isknown.

A second sensor 50, also in communication with the PCM 46, is configuredto measure the velocity of the first motor 14. Because the first motor14 may rotate in either one of two different directions, the sensor 50must measure not only the speed of rotation, but also the direction ofrotation. Similarly, a third sensor 52, also in communication with thePCM 46, is configured to measure both the speed and direction ofrotation of the second motor 16—i.e., the sensor 52 measures thevelocity of the second motor 16. Fourth and fifth sensors 54,56,similarly in communication with the PCM 46, are configured to measurethe speed of the wheels 36.

Although the sensors 54,56 do not provide the direction of rotation ofthe wheels 36, as explained more fully below, the direction of rotationmay be assumed for purposes of velocity validation. It is worth notingthat the vehicle speed may be determined from a single sensor, ratherthan two sensors, such as the sensors 54,56. Moreover, the speed of anon-drive wheel or wheels may be measured, rather than the speed of thedrive wheels as illustrated in FIG. 1.

As mentioned above, the system 10 may be used to validate the velocitiesof the engine 12 and the motors 14,16. The speed sensor 48, or asimilarly configured sensor, will be found on most vehicles, sincemeasurement of engine speed is an important parameter for vehiclecontrol. Moreover, sensors, such as the speed sensors 54,56, are alsofound on many vehicles as part of an anti-lock brake system. Validatingthe velocity of a device, such as the engine 12 or the motors 14,16,requires two independent measurements for each device. Of course, twodedicated sensors for each device can be used to perform themeasurements, but this may be a costly solution. In contrast, the system10 provides a method of velocity validation that utilizes existingsensors and relationships between the devices, such that two dedicatedsensors are not required for each device.

FIGS. 2A and 2B show a flow chart 58 illustrating a method for velocityvalidation using the system 10. The velocity validation begins at step60, and is initiated by the PCM 46. The PCM 46 may be programmed suchthat some or all of the steps shown in FIGS. 2A and 2B are repeatedlyperformed while any of the torque generating devices are running.

Initially, it may be useful to perform an availability check, wherein itis determined whether each of the inputs—i.e., each of the signals fromthe sensors 48,50,52,54,56 to the PCM 46—are functioning, see step 62.If any of the signals indicate that a sensor has a fault, or isotherwise unavailable, the faulted sensor is considered unavailable forthe velocity validation tests. As noted above, the PCM 46 is incommunication with each of the sensors 48,50,52,54,56. The communicationlink may be in the form of a controller area network (CAN). Theavailability check may also indicate that a signal has a CAN error. Whenthe PCM 46 receives such a signal, the sensor having the CAN error willbe considered unavailable.

If, in step 64, it is determined that not all of the inputs areavailable, the failed inputs are eliminated from further tests, see step66. The inputs that are available are then passed to the next set oftests, which are range tests for each of the inputs, see step 68. Ofcourse, when all the inputs were determined to be available in step 64,then all of the inputs are made available for the range tests. In step70 it is determined whether all of the inputs are within a correspondingpredetermined range. The predetermined ranges may be chosen based onknown operating ranges for each device. The predetermined ranges, orinput ranges, need not exactly match the operating range of a givendevice, but rather, may be limited or expanded as desired.

Using range tests prior to performing the velocity validation tests, maymake the method of velocity validation more robust. For example, if asensor provides an input to the PCM 46 indicating that one of thedevices or the vehicle has a velocity that is outside the input range,this may be indicative of a problem with the sensor. As shown in FIG. 3,Table 1 includes an input range for each of the variables that will beused in the velocity validation tests. For example, the engine velocity(ω_(E)) has an input range of 0 to 7000 revolutions per minute (RPM).Although the units shown in Table 1 are radians per second (RAD/S),which may be conveniently used in the validation tests, there is adirect relationship between RAD/S and RPM. Therefore, a simpleconversion factor can be employed to switch between units.

Similarly, the velocity of the first motor (ω_(M1)) has a normaloperating range of −1357 to 1357 RAD/S. The velocity of the second motor(ω_(M2)) has an input range of −943 to 943 RAD/S. Finally, the vehiclevelocity (V_(VEH)) has an input range of 0 to 300 kilometers per hour(KPH). Each of the input ranges may be programmed into the PCM 46, forexample, in the form of a lookup table. Alternatively, the input rangescould be programmed into one or more different controllers that are incommunication with the PCM 46, for example, through a CAN.

It is important to note that the input ranges shown in Table 1 aremerely one example of input ranges that may be set for a vehicle orpower producing devices within the vehicle. Thus, different vehiclearchitectures, vehicles having different power producing devices, aswell as other considerations, may lead to the assignment of input rangesdifferent from those shown in Table 1. Thus, the range tests provide aflexible tool by which inputs from the sensors 48,50,52,54,56 arechecked prior to the velocity validation tests.

Returning to FIG. 2A, it is seen that if not all of the inputs are foundto be within their corresponding input ranges in step 70, they areeliminated from further tests in step 72. The elimination of an input,either because of a failed availability check or failed range test, maypreclude a particular validation test from being performed. One methodthat can be used when this situation occurs, is to assume that the testwas performed, but that it failed. Of course, other methods may beemployed when inputs fail the range tests. Any inputs that remainavailable are then used to perform the validation tests, starting withthe first validation check in step 74. Of course, if all of the inputspass the range tests in step 70, they are all available in step 74 toperform the first validation check.

The first validation check uses the velocity of the engine 12 and themotors 14,16, and a known relationship between the velocities based onthe vehicle architecture shown in FIG. 1, to validate the velocities ofeach of the devices. Specifically, the engine speed, as measured by thesensor 48, provides an input to the PCM 46, which determines the enginevelocity based on the known direction of engine rotation. The velocityof the first and second motors 14,16 is measured by the sensors 50,52,respectively. These velocities are also provided as inputs to the PCM46.

The PCM 46 applies a preprogrammed algorithm to the inputs it receivesfrom the sensors 48,50,52. The velocities of the engine 12 and the firstand second motors 14,16 are mathematically combined and compared to afirst predetermined speed range. The preprogrammed algorithm in the PCM46 mathematically combines these terms and determines whether thismathematical combination is within the first predetermined speed range.Although a number of different equations can be used to make thisdetermination, the first equation used in the validation tests may bedefined by:

|ω_(E)−(R _(E/M1))ω_(M1)−(R _(E/M2))ω_(M2) |≦K ₁  Eq. 1

where ω_(E) is the engine velocity, ω_(M1) is the velocity of the firstmotor, ω_(M2) is the velocity of the second motor, R_(E/M1) is a ratioof the engine velocity to the velocity of the first motor, R_(E/M2) is aratio of the engine velocity to the second motor, and K₁ is a firstpredetermined speed.

The ratios used in Equation 1, R_(E/M1) and R_(E/M2), are first andsecond velocity relationships that are based on the vehiclearchitecture. Specifically, the planetary gear set 18 provides a knownrelationship between the velocity of the engine 12 and the velocity ofthe first motor 14. Where other power transfer units are used, differentrelationships may exist between the velocities of the engine 12 and thefirst motor 14. Similarly, a known relationship exists between thevelocity of the engine 12 and the velocity of the second motor 16, basedon the planetary gear set 18 and the second gear set 38. Applying theserelationships to the velocities of the first and second motors 14,16allows the velocities of each of the three power producing devices to bevalidated, using a single sensor at each device.

The left-hand side of Equation 1 represents a first combined speed term,which is then compared to the first predetermined speed range, definedin Equation 1 as any speed less than or equal to K₁. The mathematicalcombination used to develop the first combined speed term may assume anumber of different forms and still be useful for velocity validation.For example, the sign of any of the terms can be changed, the order ofthe terms can be rearranged, or one of the motor velocities can be usedwithout a ratio applied to it, while a different ratio—e.g., a motorvelocity to engine velocity ratio (R_(M/E))—is applied to the enginevelocity. In any of these cases, Equation 1 would still be valid,provided that K₁ was assigned an appropriate value that defined thecorrect predetermined speed range for the mathematical combination onthe left side of the equation.

Turning to FIG. 2B, it is determined at step 76 whether the firstvalidation check passed—i.e., whether the first combined speed term waswithin the first predetermined speed range. If the first validationcheck passes, then the velocity of each power producing device—theengine 12 and the motors 14,16—are validated; this is shown in step 78.If, however, the first combined speed term was not within the firstpredetermined speed range, a second velocity validation check may beperformed, see step 80.

The second velocity check, as performed in step 80, provides a method tovalidate the velocity of the second motor. As described above, thevelocity of the second motor is measured directly by the sensor 52;however, it is necessary to have another velocity measurement in orderto confirm that the velocity measured by the sensor 52 is valid. Ratherthan adding a second velocity sensor to the second motor 16, theexisting vehicle speed sensors 54, 56 are used, which saves the cost ofan additional velocity sensor. As described above, the speed sensors 54,56 are not capable of determining the direction of rotation of thewheels 36. Therefore, the second validation check, which uses a secondequation, will perform an evaluation of the second equation two times.The first time the second equation is evaluated, a positive sign isassigned to the vehicle speed; the second time it is evaluated, anegative sign is assigned to the vehicle speed.

Each of the sensors 54, 56 provides a measurement of the speed of thewheels 36, which is indicative of the vehicle speed. In order to get asingle value for the vehicle speed, the measurements from the sensors54, 56 may be mathematically combined, for example, by using an averagevalue of the two measured speeds. Thus, the determination of the vehiclespeed may include measuring the wheel speed with the sensor 54 and thesensor 56, and then taking the average of the two wheel speeds. Ofcourse, the measured speeds may be combined using some othermathematical combination, or a single sensor may be used, as desired.

Because the vehicle velocity will typically have units such as KPH, itwill be necessary to convert the units into RAD/S to be compatible withthe velocity of the second motor 16 as measured by the sensor 52. Thesecond validation check can then be performed by mathematicallycombining the velocity of the second motor 16 and the determined vehiclespeed, and then comparing this mathematical combination to a secondpredetermined speed range to validate the velocity of the second motor16. Although various forms of the second equation may be used for thesecond validation check, one form of the equation is defined by:

|ω_(M2)−(C ₁)V _(VEH) |<K ₂  Eq. 2

where ω_(M2) is the velocity of the second motor, C₁ is a constant usedto change units of vehicle velocity into radians per second, V_(VEH) isthe determined vehicle velocity, and K₂ is a second predetermined speed.

Just as with the first equation, the second equation includes amathematical combination of velocities on the left side of the equation,which may be called a “second combined speed term.” The secondpredetermined speed range is defined as any speed less than the secondpredetermined speed (K₂). As with the first combined speed term in thefirst equation, the second combined speed term in Equation 2 may also berearranged using a different order of the terms, or applying differentsigns to the terms. Of course, the second predetermined speed (K₂) wouldneed to be chosen appropriately; however, variations of Equation 2involving different mathematical combinations of the velocity of thesecond motor 12 and the vehicle velocity are contemplated within thepresent invention.

As noted above, the speed sensors 54, 56 do not provide a direction forthe rotation of the wheels 36. Therefore, Equation 2 is evaluated twice:a first time wherein the determined vehicle velocity is given a positivesign, and a second time wherein the vehicle velocity is given a negativesign. In each case, it is required that the relationship expressed inEquation 2 holds. Stated another way, the second combined speed term isgenerated twice, and each time it is required to be within the secondpredetermined speed range.

Returning to FIG. 2B, the determination of whether the second velocitycheck passes occurs at step 82. If Equation 2 is found to hold when thevehicle velocity is given a positive sign and when it is given anegative sign, the second validation check has passed. When this occurs,the velocity of the second motor 16 is validated, see step 84. IfEquation 2 does not hold for either the positive or negative value ofvehicle velocity, a third validation check may be performed, see step86.

For the third validation check, the PCM 46 mathematically combines thevelocities of the engine 12 and the first motor 14, with the determinedvehicle speed to generate a third combined speed term. The thirdcombined speed term is then compared to a third predetermined speedrange for purposes of validating the velocities of the engine 12 and thefirst motor 14. Specifically, a third equation is used that is similarto the first equation, except that the term that included the velocityof the second motor 16 is replaced by the determined vehicle velocityterm. It is worth noting that just as with Equations 1 and 2, Equation 3may assume different forms. Thus, Equation 3 may be defined by:

|ω_(E)(R _(E/M1))ω_(M1)−(C ₁)V _(VEH) |≦K ₃  Eq. 3

where ω_(E) is the engine velocity, ω_(M1) is the velocity of the firstmotor, R_(E/M1) is a ratio of the engine velocity to the velocity of thefirst motor, C₁ is a constant used to change units of vehicle velocityinto radians per second, V_(VEH) is the determined vehicle velocity, andK₃ is a third predetermined speed.

Because equation 3 involves the determined vehicle velocity, it must beevaluated twice, just as Equation 2 is evaluated twice. Thus, thedetermined vehicle velocity is assigned a positive sign the first timeEquation 3 is evaluated, and a negative sign the second time it isevaluated. Returning to FIG. 2B, a determination is made at step 88whether the third validation check has passed. If the third validationcheck passes, the velocities of the engine 12 and the first motor 14 arevalidated. If, however, the third validation check does not pass, thennone of the velocities are validated, see step 92.

As described above, the system 10 shown in FIG. 1 can be used with anyof a variety of vehicle architectures. For example, FIG. 4 shows aschematic representation of a system 94, which is an alternativeembodiment of the present invention. A vehicle, not shown in itsentirety, includes an engine 96 and a first motor, or combinedmotor/generator 98. A disconnect clutch 100 is disposed between theengine 96 and the motor/generator 98 for selectively connecting anddisconnecting the engine 96 to the wheels 102. The motor/generator 98 isconnected to a power transfer unit (PTU) 104, which transfers power fromthe motor/generator 98 to the wheels 102. The PTU 104 may be virtuallyany device or system for transferring power, including, but not limitedto, gear sets, automatic or manual transmissions, or converterlesstransmissions.

A battery 106 is electrically connected to the motor/generator 98 forproviding electrical power to the motor/generator 98 when it is beingoperated as a motor to drive the wheels 102. Alternatively, themotor/generator 98 may act as a generator to recharge the battery 106,when the vehicle is in a regenerative mode. Similar to the configurationshown in FIG. 1, the engine 96 is equipped with a speed sensor 108 whichfacilitates a determination of the engine velocity; the velocity can bedetermined with a speed sensor, since the engine 96 rotates in only onedirection. A sensor 110 is provided for measuring the velocity of themotor/generator 98. Moreover, speed sensors 112,114 are provided at thewheels 102 to facilitate a determination of the vehicle velocity. Acontroller, in the embodiment shown in FIG. 4, a PCM 116, is incommunication with a transaxle 118, the engine 96, and each of thesensors 108,110,112,114.

As with the vehicle architecture shown in FIG. 1, the vehiclearchitecture in FIG. 4 includes three sensors 108,112,114 that arenormally provided on many vehicles, and therefore do not require aspecial purchase or installation. Because the vehicle shown in FIG. 4includes only a first motor, the motor/generator 98, only one additionalsensor, the sensor 110, is needed to validate the velocities of theengine 96 and the motor/generator 98. It will be apparent to one skilledin the art, that minor modifications to equations 1-3 are all that isneeded to provide a method for validating the velocities of torquegenerating devices in a vehicle having an architecture similar to thatshown in FIG. 4. For example, a modified version of equation one may bedefined by:

|ω_(E)(R _(E/MG))ω_(MG) |≦K ₁ A  Eq. 1A

where ω_(E) is the engine velocity, ω_(MG) is the velocity of the firstmotor, or motor/generator 98, R_(E/MG) is a ratio of the engine velocityto the velocity of the motor/generator, and K_(1A) is a firstpredetermined speed.

The ratio used in Equation 1A, (R_(E/MG)), is a first velocityrelationship that is based on the vehicle architecture shown in FIG. 4.For example, when the disconnect clutch 100 is closed, a knownrelationship exists between the velocities of the engine 96 and themotor/generator 98. When the disconnect clutch 100 is open, however,there is no such velocity relationship, and Equation 1A cannot be used.Just as with Equations 1-3, Equation 1A may assume different forms,provided the appropriate value for K_(1A) is chosen. When Equation 1Aholds,—i.e., if the first validation check passes—only the velocities ofthe engine 96 and the motor/generator 98 are validated. There is nosecond motor in this configuration that requires a velocity validation.

The second validation check will remain largely unaltered for thevehicle architecture shown in FIG. 4. For example, a second equation,equation 2A, used for the second validation check for a vehicle havingthe architecture shown in FIG. 4, may be defined by:

|ω_(MG)−(C ₁)V _(VEH) |<K ₂ A  Eq. 2A

where ω_(MG) is the velocity of the first motor, or motor/generator 98,C₁ is a constant used to change units of vehicle velocity into RAD/S,V_(VEH) is the determined vehicle velocity, and K_(2A) is a secondpredetermined speed.

Thus, a mathematical combination of the velocity of the motor/generator98 and the determined vehicle speed is compared to a secondpredetermined speed range. As with the other equations, the mathematicalcombination on the left hand side of equation 2A may be rearranged asdesired, provided an appropriate value of K_(2A) is chosen. As withEquation 2, and all of the equations involving the determined vehiclevelocity, Equation 2A must be evaluated twice, with the determinedvehicle velocity being given a different sign each time. If Equation 2Aholds for each of the two evaluations, the second validation check haspassed. When this occurs, the velocity of the first motor, or themotor/generator 98, is validated. If this does not occur, a thirdvalidation check may be used.

For the vehicle architecture shown in FIG. 4, the third validation checkinvolves the use of a third equation, which may be defined by:

ω_(E)(C ₁)V _(VEH) |≦K ₃ A  Eq. 3A

where ω_(E) is the engine velocity, C₁ is a constant used to changeunits of vehicle velocity into RAD/S, V_(VEH) is the determined vehiclevelocity, and K_(3A) is a third predetermined speed. Because Equation 3Auses the vehicle velocity, it is evaluated twice, giving the vehiclevelocity a different sign each time. Moreover, Equation 3A, as with anyof the previous equations, may assume different forms, provided anappropriate value for K_(3A) is chosen. If both evaluations of Equation3A hold, then the engine velocity is validated.

Although the vehicle architectures shown in FIG. 1 and FIG. 4 appear tobe markedly different, there is some similarity. For example, the motorbrake 30, shown in FIG. 1, may be selectively applied to stop rotationof the motor shaft 28 and the sun gear 24. In such a situation, thevehicle architecture of FIG. 1 resembles the vehicle architecture ofFIG. 4, wherein the planetary gear set 18 and the second gear set 38 arerepresented by the PTU 104 in FIG. 4. Of course, the system 10 may beused with a variety of different vehicle architectures, it beingunderstood that the architectures illustrated in FIGS. 1 and 4 representjust two examples.

While the best mode for carrying out the invention has been described indetail, those familiar with the art to which this invention relates willrecognize various alternative designs and embodiments for practicing theinvention as defined by the following claims.

1. A system for validating engine and motor velocities in a vehiclehaving a plurality of vehicle components, including an engine and afirst motor arranged in a vehicle architecture such that at least oneknown mathematical relationship exists between the engine velocity andthe velocity of the first motor, the system comprising: a first sensorconfigured to measure engine speed, thereby facilitating a determinationof engine velocity; a second sensor configured to measure the velocityof the first motor; and a controller in communication with the first andsecond sensors, and configured to determine whether a mathematicalcombination of at least the engine velocity and the velocity of thefirst motor is within a first predetermined speed range, the enginevelocity and the velocity of the first motor being validated when themathematical combination is within the first predetermined speed range,the controller being further configured to communicate at least one ofthe validated engine velocity or the validated velocity of the firstmotor to at least one of the vehicle components.
 2. The system of claim1, the vehicle further including at least one drive wheel, the systemfurther comprising at least one other sensor in communication with thecontroller and configured to measure the speed of a respective one ofthe at least one drive wheel, thereby facilitating a determination ofvehicle speed by the controller, the controller being further configuredto determine whether a mathematical combination of the velocity of thefirst motor and the determined vehicle speed is within a secondpredetermined speed range when the mathematical combination of theengine velocity and the velocity of the first motor are not within thefirst predetermined speed range.
 3. The system of claim 2, the vehicleincluding two of the drive wheels, and wherein the system includes twoof the other sensors, the controller being configured to determine thevehicle speed based on a mathematical average of the wheel speedsmeasured by the two other sensors.
 4. The system of claim 2, wherein thecontroller is further configured to twice determine whether themathematical combination of the velocity of the first motor and thedetermined vehicle speed is within the second predetermined speed range,the determined vehicle speed being given an opposite sign in each of thetwo determinations, the velocity of the first motor being validated whenthe mathematical combination of the velocity of the first motor and thedetermined vehicle speed is within the second predetermined speed rangeregardless of the sign given to the determined vehicle speed, thecontroller being further configured to communicate the validatedvelocity of the first motor to at least one of the vehicle components.5. The system of claim 2, wherein the controller is further configuredto twice determine whether a mathematical combination of the enginevelocity and the determined vehicle speed is within a thirdpredetermined speed range, the determined vehicle speed being given anopposite sign in each of the two determinations, the engine velocitybeing validated when the mathematical combination of the engine velocityand the determined vehicle speed is within the third predetermined speedrange regardless of the sign given to the determined vehicle speed, thecontroller being further configured to communicate the validated enginevelocity to at least one of the vehicle components.
 6. The system ofclaim 2, the vehicle further including a second motor arranged in thevehicle architecture such that at least one known mathematicalrelationship exists between the engine velocity and the velocity of thesecond motor, the system further comprising a third sensor configured tomeasure the velocity of the second motor, and wherein the controller isfurther configured to include the velocity of the second motor in themathematical combination of the engine velocity and the first vehiclespeed, the engine velocity, the velocity of the first motor, and thevelocity of the second motor being validated when the mathematicalcombination of the engine velocity and the velocities of the first andsecond motors is within the first predetermined speed range, thecontroller being further configured to communicate at least one of thevalidated engine velocity, the validated velocity of the first motor, orthe validated velocity of the second motor to at least one of thevehicle components.
 7. The system of claim 6, wherein the controller isfurther configured to determine whether a mathematical combination ofthe velocity of the second motor and the determined vehicle speed iswithin the second predetermined speed range when the mathematicalcombination of the engine velocity and the velocities of the first andsecond motors is not within the first predetermined speed range, thevelocity of the second motor being validated when the mathematicalcombination of the velocity of the second motor and the determinedvehicle speed is within the second predetermined speed range, thecontroller being further configured to communicate the validatedvelocity of the second motor to at least one of the vehicle components.8. A system for validating engine and motor velocities in a vehiclehaving a plurality of vehicle components, including an engine, a firstmotor, and a second motor arranged in a vehicle architecture such thatat least one known mathematical relationship exists between the enginevelocity and each of the velocities of the first and second motors, thesystem comprising: a first sensor configured to measure engine speed,thereby facilitating a determination of engine velocity; a second sensorconfigured to measure the velocity of the first motor; a third sensorconfigured to measure the velocity of the second motor; and a controllerin communication with the first, second and third sensors, andconfigured to combine the engine velocity and the velocities of thefirst and second motors to generate a first combined speed term andcompare the first combined speed term to a first predetermined speedrange, the engine velocity and the velocities of the first and secondmotors being validated when the first combined speed term is within thefirst predetermined speed range, the controller being further configuredto communicate at least one of the validated determined engine velocity,the validated measured velocity of the first motor, or the validatedmeasured velocity of the second motor to at least one of the vehiclecomponents.
 9. The system of claim 8, the vehicle further including atleast one drive wheel, the system further comprising at least one othersensor in communication with the controller and configured to measurethe speed of a respective one of the at least one drive wheel, therebyfacilitating a determination of vehicle speed by the controller, thecontroller being further configured to: mathematically combine themeasured velocity of the second motor and the determined vehicle speedto generate a second combined speed term, compare the second combinedspeed term to a second predetermined speed range, the measured velocityof the second motor being validated when the second combined speed termis within the second combined speed range, and communicate the validatedmeasured velocity of the second motor to at least one of the vehiclecomponents.
 10. The system of claim 9, the vehicle including two of thedrive wheels, and wherein the system includes two of the other sensors,the controller being configured to determine the vehicle speed based ona mathematical average of the wheel speeds measured by the two othersensors.
 11. The system of claim 9, wherein the controller is configuredto generate the second combined speed term twice, a first time with thedetermined vehicle speed being given a positive sign, and a second timewith the determined vehicle speed being given a negative sign, andwherein the measured velocity of the second motor is validated only whenboth of the generated second combined speed terms are within the secondpredetermined speed range.
 12. The system of claim 9, wherein thecontroller is further configured to: mathematically combine thedetermined engine velocity, the measured velocity of the first motor,and the determined vehicle speed to generate a third combined speedterm, compare the third combined speed term to a third predeterminedspeed range, the determined engine velocity and the measured velocity ofthe first motor being validated when the third combined speed term iswithin the third predetermined speed range, and communicate at least oneof the validated determined engine velocity or the validated measuredvelocity of the first motor to at least one of the vehicle components.13. The system of claim 12, wherein the controller is configured togenerate the third combined speed term twice, a first time with thedetermined vehicle speed being given a positive sign, and a second timewith the determined vehicle speed being given a negative sign, andwherein the determined engine velocity and the measured velocity of thefirst motor are validated only when both of the generated third combinedspeed terms are within the third predetermined speed range.
 14. Thesystem of claim 13, wherein the controller is further configured todetermine whether the measured engine speed, the measured velocity ofthe first motor, the measured velocity of the second motor, and thedetermined vehicle speed are each within a corresponding predeterminedrange prior to generating any of the combined speed terms.
 15. A systemfor validating component velocities in a vehicle having a plurality ofvehicle components, at least one pair of the vehicle components beingarranged in a vehicle architecture such that a respective knownmathematical relationship exists between the respective velocities ofthe vehicle components in each of the at least one pair, the systemcomprising: a first sensor configured to measure at least one of avelocity or speed of a first of the vehicle components; a second sensorconfigured to measure at least one of a velocity or speed of a second ofthe vehicle components, the first and second vehicle components beingarranged in one of the pairs of vehicle components; a controller incommunication with the first and second sensors, and configured to:calculate a velocity of the first vehicle component when the firstsensor is configured to measure speed, calculate a velocity of thesecond vehicle component when the second sensor is configured to measurespeed, determine whether a mathematical combination of at least thevelocities of the first and second vehicle components is within a firstpredetermined speed range, the velocities of the first and secondvehicle components being validated when the mathematical combination iswithin the first predetermined speed range, and communicate at least oneof the validated velocities of the first and second vehicle componentsto at least one of the vehicle components.
 16. The system of claim 15,wherein the velocity of one of the vehicle components in the at leastone pair is a velocity of the vehicle.
 17. The system of claim 15,wherein the first and second vehicle components respectively include anengine and a first motor.
 18. The system of claim 17, wherein thevehicle components further include a second motor arranged in another ofthe pairs of vehicle components with one of the engine or the firstmotor, the system further comprising a third sensor configured tomeasure the velocity of the second motor, the controller being furtherconfigured to: include the velocity of the second motor in themathematical combination, the engine velocity, the velocity of the firstmotor, and the velocity of the second motor being validated when themathematical combination of the engine velocity and the velocities ofthe first and second motors is within the first predetermined speedrange, and communicate at least one of the validated engine velocity,the validated velocity of the first motor, or the validated velocity ofthe second motor to at least one of the vehicle components.
 19. A systemfor validating engine and motor velocities in an automotive vehicle, thesystem comprising: a first sensor configured to measure engine speed,thereby facilitating a determination of engine velocity; a second sensorconfigured to measure the velocity of a motor; and a controller, incommunication with the first and second sensors, configured to: validatethe engine velocity and the motor velocity when a mathematicalcombination thereof is within a predetermined speed range, andcommunicate at least one of the validated engine velocity or thevalidated motor velocity to a vehicle component.